Intracellular microrheology of motile amoeba proteus

Salman S. Rogers, Thomas A. Waigh, Jian R. Lu

    Research output: Contribution to journalArticlepeer-review

    Abstract

    The motility of Amoeba proteus was examined using the technique of passive particle tracking microrheology, with the aid of newly developed particle tracking software, a fast digital camera, and an optical microscope. We tracked large numbers of endogeneous particles in the amoebae, which displayed subdiffusive motion at short timescales, corresponding to thermal motion in a viscoelastic medium, and superdiffusive motion at long timescales due to the convection of the cytoplasm. Subdiffusive motion was characterized by a rheological scaling exponent of 3/4 in the cortex, indicative of the semiflexible dynamics of the actin fibers. We observed shear-thinning in the flowing endoplasm, where exponents increased with increasing flow rate; i.e., the endoplasm became more fluid-like. The rheology of the cortex is found to be isotropic, reflecting an isotropic actin gel. A clear difference was seen between cortical and endoplasmic layers in terms of both viscoelasticity and flowvelocity, where the profile of the latter is close to a Poiseuille flow for a Newtonian fluid. © 2008 by the Biophysical Society.
    Original languageEnglish
    Pages (from-to)3313-3322
    Number of pages9
    JournalBIOPHYSICAL JOURNAL
    Volume94
    Issue number8
    DOIs
    Publication statusPublished - 15 Apr 2008

    Keywords

    • PARTICLE-TRACKING MICRORHEOLOGY
    • DIFFUSING WAVE SPECTROSCOPY
    • FLUORESCEIN-LABELED ACTIN
    • AMEBA-PROTEUS
    • LIVING CELLS
    • FILAMENT
    • NETWORKS
    • COMPLEX FLUIDS
    • SOFT MATERIALS
    • MECHANICS
    • CYTOSKELETON

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